Heatable stage for a microscope



Och 1969 R. SCHEIDEGGER 3,472,726

HEATABLE STAGE FOR A MICROSCOPE Filed March 6, 1968 INVENTOR? find 1% up BY! fl mew-v United States Patent 3,472,726 HEATABLE STAGE FOR A MICROSCOPE Ren Scheidegger, Durnten, Switzerland, assignor to Mettler Instrumentc, A.G., Zurich, Switzerland, a Swiss corporation.

Filed Mar. 6, 1968, Ser. No. 711,106 Claims priority, application Switzerland, June 12, 1967,

,2 3/ 7 Int. Cl. G02b 21/30; F28f 13/12, 19/00 US. Cl. 165-48 Claims ABSTRACT OF THE DISCLOSURE Stages for microscopic examination under heat comprise a furnace containing a chamber, into which the specimen to be examined is usually inserted by means of specimen holders. The furnace itself is generally accommodated inside a housing which may be fixed on the table of a microscope. Apertures are provided in the furnace and in the housing to enable the specimen to be illuminated and observed.

According to the examination to be carried out, high temperatures of up to some hundreds of degrees centigrade are sometimes required. At such temperatures the amount of heat radiated by the furnace per unit of area is considerable. In order to avoid any damage to the objective of the microscope, the objective cannot in such cases be brought too close to the furnace. However, if a certain safety gap is left between the objective and the furnace, the optical enlargement possible with a given microscope will be correspondingly reduced. Even with comparatively low temperatures of up to about 100 degrees centigrade it is inevitable, if greater optical enlargements are to be obtained, for the furnace to be as small as possible in the observing direction and thus for it to be shallow enough to enable sufiiciently small spacings to be left between the specimen and the objective. On the other hand, shallow furnaces of this type produce greatly varying temperature gradients within the housing of the stage, and after a long period of observation result in uneven heating. And finally, considerable difliculty is often met in ascertaining the temperature at the location of the specimen with suflicient accuracy, or in altering it according to a predetermined temperature time program.

For these and similar reasons the detailed construction of heatable stages has been made to meet the specific requirements of the examination to be carried out, and the compromises which were found necessary from case to case have had to be accepted. Apparatus for carrying out the usual therrnomicroscopic examinations often required in the laboratory therefore usually comprises, apart from the microscope, a large number of heatable stages of different construction and serving different purposes.

The primary object of the present invention is to provide a heatable stage for thermomicroscopic examinations which may be employed for most of the examinations conventionally carried out in a laboratory, in which the behavior of a specimenunder heat is studied under a microscope. This is achieved, in accordance with the present 3,472,726 Patented Oct. 14, 1969 invention, by providing in a heatable stage for a microscope, an outer housing arranged to be mounted on a microscope table, an inner housing mounted within said outer housing with a cavity between the outer and inner housing, a furnace mounted within said inner housing and containing a chamber for the specimen to be examined, said outer and inner housing and said furnace having apertures for illuminating and observing said specimen, and means to pass a cooling airstream through said cavity during examination of said specimen.

Other objects and advantages of the invention will become apparent from a study of the following specification when considered in connection with the accompanying drawing, in which the single figure is a somewhat diagrammatic view-with certain parts shown in section-of the heatable stage for a microscope according to the present invention. Any details not necessary to an understanding of the invention have been omitted for reasons of clarity.

Referring to the drawing, in the position of use the heatable stage is fixed as usual onto the microscope table 1, which is shown only partially in the drawing and contains an aperture 2 for illumination. A fragment of the objective 3 is also illustrated but otherwise no further parts of the microscope are included in the drawing.

The outer housing 4 of the heatable stage is preferably made of sheet metal and contains an inner housing 6, preferably also made of sheet metal, with a cavity 5 extending throughout between the housings 4 and 6. The inner housing 6 is supported in the outer housing 4 by means of a plurality of metal props 7. These pass through the cavity 5 and establish a heat conductive connection between the inner housing 6 and the outer housing 4. The inner housing 6 in turn encloses a furnace 8 which is separated therefrom on all sides and attached thereto in a heat insulating manner by means of a plurality of ceramic props 9. The specimen chamber 10 of the furnace is inside the body of the latter, which is provided in the usual way with electrical heating elements (not shown) and an electrical temperature sensor. For the purpose of observing and illuminating the specimen in the chamber 10, the outer housing 4 has apertures 11 and 12, the inner housing 6 has coaxial apertures 13 and 14 and the furnace 8 has corresponding apertures 15 and 16 which lead into the specimen chamber 10.

The apertures 13 and 14 are each covered with a glass disc 17 and 18 respectively, the discs 17 and 18 being fixed to the inner housing 6, and preferably being designed in known manner as heat protective filters. The size of the aperture 11 is such that the objective 3 of the microscope can pass through it and enter the cavity 5. The bottom aperture 12 is aligned with the illuminating aperture 2 of the microscope table 1. The aperture 2 is itself covered by the optical illuminating means which are mounted below the table 1 but not illustrated in the drawmg.

A motor driven fan 19 is attached to the outer housing 4 to the left of the inner housing 6. Its blade 20 sucks up fresh air through the aperture 21 in the outer housing 4, forces it through the cavity 5 from left to right and ejects it through the outlet 22 provided at the right hand side of the outer housing 4. Hence the direction in which the air stream conveyed by the fan 19 passes through the cavity 5 is substantially at right angles to the direction in which the specimen in the chamber 10 is illuminated and observed through the apertures 11 to 1-6. At the side away from the fan 19 the inner housing 6 contains an insertion aperture 23 opening towards the outlet 22 in the outer housing 4. An insertion aperture 24 for the specimen chamber 10 provided in the furnace 8 similarly opens towards the aperture 23 in the inner housing 6. The end portion of the specimen holder 25, which carries the specimen to be examined and is usually made of glass, can accordingly be introduced into the chamber 10 through the outlet 22 of the outer housing 4, the aperture 23 in the inner housing 6 and the aperture 24 in the furnace 8.

A cross slide 26 of conventional construction is finally mounted on the outer housing 4 at the same side as the outlet 22, so that the end portion of the specimen holder 25 in the specimen chamber 10 can be slid as required in order to centre the specimen in the optical axis of the microscope.

When the heatable stage described is in use the motor driven fan 19 is kept in operation throughout the examination. The inner housing 6 thus has a cooling airstream permanently flowing around it, which continuously carries away the heat radiated into the housing 6 by the furnace 8. Undesirable accumulation of heat can accordingly occur neither in the furnace 8 nor within the inner housing 6, so any desired temperature for the specimen chamber 10 can be obtained very rapidly and accurately controlled. The airstream conveyed through the cavity further provides an effective cooling action for the objective 3, which accordingly can be brought near the inner housing 6. A final important point is that virtually the whole temperature gradient starting from the furnace 8 is concentrated in the space between the furnace 8 and the inner housing 6, which enables comparatively small dimensions to be used for the inner housing 6 in the direction in which the specimen is observed and illuminated.

By virtue of its favourable properties the heatable stage described can be employed for most of the examinations conventionally carried out in a laboratory, in which the behaviour of a specimen under heat is studied under a microscope. Without any adjustments or alterations having to be made to the heatable stage and its associated control means it is possible, for example, to measure micro melting points, to ascertain eutectic temperatures, to obtain optical constants of melts by the glass powder method, to examine polymorphous substances, to carry out heat analysis by the contact method and to conduct microbiological examinations.

While in accordance with the provisions of the Patent Statutes, the preferred form and embodiments of the invention have been illustrated and described, it will be apparent to those skilled in the art that modifications may be made without deviating from the invention as set forth in the following claims.

What is claimed is:

1. A heatable stage for a microscope, including an outer housing arranged to be mounted on a microscope table, an inner housing mounted within said outer housing with a cavity between said outer and inner housings, a furnace mounted within said inner housing and containing a chamber for the specimen to be examined, said outer and inner housings and said furnace having apertures for illuminating and observing said specimen, and means to pass a cooling airstream through said cavity during examination of said specimen.

2. A heatable stage as defined in claim 1, wherein said means are arranged to pass said cooling airstream through said cavity in a direction which is at right angles to the direction in which said specimen is illuminated and observed through said apertures.

3. A heatable stage as defined in claim 1, wherein said apertures in said inner housing are each covered with a glass disc which is fixed to said inner housing, and wherein the size of said aperture provided in the outer housing for the purpose of observing said specimen is such that the objective of the microscope can be introduced through it into said cavity.

4. A heatable stage as defined in claim 1, wherein said means comprise a motor driven fan mounted on said outer housing, said fan sucking air through an inlet in said outer housing, conveying it through said cavity and ejecting the heated air through an outlet in said outer housing.

5. A heatable stage as defined in claim 4, wherein said inner housing has a specimen insertion aperture opening towards said outlet in the outer housing, and said furnace has a specimen insertion aperture leading to the specimen chamber and opening towards said insertion aperture in said inner housing.

6. A heatable stage as defined in claim 1, wherein said furnace is fixed to said inner housing in a heat insulating manner and saidinner housing is fixed to said outer housing in a heat conductive manner.

7. A heatable stage as defined in claim 4, wherein said fan has a blade arranged within said outer housing.

References Cited UNITED STATES PATENTS 2,959,090 11/1960 Davies 35063 3,310,356 3/1967 Borberg 350-63 3,361,192 1/1968 Dexter 122 ROBERT A. OLEARY, Primary Examiner C. SUKALO, Assistant Examiner US. Cl. X.R. 

